Reversible battery assembly and tooling for automated high volume production

ABSTRACT

A battery module includes a plurality of battery cells arranged in a stack, each of the battery cells including a pair of spaced apart tabs extending therefrom, a rigid support plate coupled to at least one of the tabs, and a busbar coupled to at least one of the tabs of each of a pair of adjacent battery cells.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. patent applicationSer. No. 12/727,503, filed on Mar. 19, 2010. The entire disclosure ofthe above application is incorporated herein by reference.

FIELD OF THE INVENTION

The present invention generally relates to a battery module having aplurality of battery cells. In particular, the invention is directed toa battery module and a method for assembling the battery module.

BACKGROUND OF THE INVENTION

A battery assembly for hybrid, plug-in electric (EV), or other typevehicles includes a plurality of battery cells. Cooling fins, repeatingframes and foams, and electrical interconnects are joined to the batterycells to form a battery module or battery pack. The battery module for along driving range EV may contain more than two hundred battery cells.

Currently, after stacking and assembling the battery cells and othercomponents into the battery module, every two or three adjacent batterycells are welded together with U-channel sheet metals to formserial/parallel electric connections. Specifically, each of the batterycells has at least two tabs or electric terminals (one positive, onenegative) that are welded to the U-channel sheet metals. In certainapplications, the tabs of each of the battery cells are bent such thatthe tips of the tabs are aligned after welding. Unfortunately, due tothe difficulty of precise tab bending and position control duringwelding, uneven tab height still exists. Uneven and misaligned tabsaffect the overall weld quality between the tabs and the U-channelsheets and pose a risk of short circuiting due to tab interference.

Furthermore, because of the irreversible nature of current weldingtechniques, such as spot welding and ultrasonic welding, removing adefective or “bad” battery cell from a fully assembled battery modulerequires cutting all of the tab connections in the battery module,thereby rendering the “good” battery cells unusable for re-weld orrestoration to another battery module.

It would be desirable to develop a battery module and a method ofassembling the battery module, wherein the battery module is repairableand remanufacturable at a minimal effort and cost, while maintaining aflexibility in serial/parallel connection of a plurality of batterycells as well as minimizing an occurrence of uneven tab alignment.

SUMMARY OF THE INVENTION

Concordant and consistent with the present invention, a battery moduleand a method of assembling the battery module, wherein the batterymodule is repairable and remanufacturable at a minimal effort and cost,while maintaining a flexibility in serial/parallel connection of aplurality of battery cells as well as minimizing an occurrence of uneventab alignment, has surprisingly been discovered.

In one embodiment, a battery module comprises: a plurality of batterycells arranged in a stack, each of the battery cells including a pair ofspaced apart tabs extending therefrom; a rigid support plate coupled toat least one of the tabs; and a busbar coupled to at least one of thetabs of each of a pair of adjacent battery cells.

In another embodiment, an apparatus for assembling a battery modulehaving a plurality of battery cells comprises: a base; a grill carriermoveable relative to the base; and a grill rod coupled to the grillcarrier, the grill rod having a main body with a longitudinal axisgenerally parallel to the base.

The invention also provides methods of assembling a battery module.

One method comprises the steps of: providing an apparatus having a base,a grill carrier moveable relative to the base, and a grill rod coupledto the grill carrier; disposing a plurality of battery cells on the basein a stacked relationship, each of the battery cells having a pair oftabs extending therefrom; moving the grill carrier toward the batterycells to dispose the grill rod between at least one tab of each of anadjacent pair of the battery cells; and coupling a busbar to the atleast one tab of each of an adjacent pair of the battery cells.

BRIEF DESCRIPTION OF THE DRAWINGS

The above, as well as other advantages of the present invention, willbecome readily apparent to those skilled in the art from the followingdetailed description of the preferred embodiment when considered in thelight of the accompanying drawings in which:

FIG. 1 is an exploded perspective view of a battery module according toan embodiment of the present invention;

FIG. 2A is a front elevational view of a battery cell assembly accordingto an embodiment of the present invention;

FIG. 2B is a side elevational view of the battery cell assembly of

FIG. 2A;

FIG. 3A is a side elevational view of a busbar according to anembodiment of the present invention, showing a cut-away portion of thebusbar;

FIG. 3B is a front elevational view of the busbar of FIG. 3A;

FIG. 4 is a front elevational view of a grill fixture according to anembodiment of the present invention;

FIG. 5A is a bottom plan view of a grill rod of the grill fixture ofFIG. 4;

FIG. 5B is a side elevational view of a grill rod of the grill fixtureof FIG. 4;

FIG. 6 is a front elevational view of the grill fixture of FIG. 4,showing a stack of battery cells disposed on a base thereof;

FIG. 7A is a front elevational view of the grill fixture of FIG. 4during an assembly process;

FIG. 7B is a side elevational view of the grill fixture of FIG. 4 duringan assembly process; and

FIG. 8 is a top plan view of the battery module of FIG. 1 with a controlplate removed.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS OF THE INVENTION

The following detailed description and appended drawings describe andillustrate various embodiments of the invention. The description anddrawings serve to enable one skilled in the art to make and use theinvention, and are not intended to limit the scope of the invention inany manner. In respect of the methods disclosed, the steps presented areexemplary in nature, and thus, the order of the steps is not necessaryor critical.

FIGS. 1-3 illustrate a battery module 10 according to an embodiment ofthe present invention. As shown, the battery module 10 includes aplurality of battery cells 12, each of the battery cells 12 having apair of tabs 14 (i.e. terminals), and a plurality of busbars 16 adaptedto be coupled to the tabs 14. The battery module 10 further includes acontrol plate 18 disposed adjacent the busbars 16 and in electricalcommunication therewith. It is understood that each of the battery cells12 can be a battery cell assembly including a plurality of stackedbattery cells.

A support plate 20 is coupled to each of the tabs 14. As a non-limitingexample, the support plate 20 is formed from a rigid non-conductivematerial similar to a material used in conventional printed circuitboards. However, other materials can be used. The support plate 20includes a protuberance, referred to as a key 22, which is relied uponduring the assembly operation, described herein below.

In certain embodiments, each of the tabs 14 is bent around a portion ofthe support plate 20 to increase a contact area between the tab 14 andthe busbar 16. In other embodiments, the support plate 20 is adhered toa surface of the tab 14 without a bending or forming process. It isunderstood that any means of coupling the support plates 20 to the tabs14 can be used. It is further understood that the support plates 20provide a stiffness to the tabs 14, while allowing the tab 14 tomaintain a flexible root portion 23 connecting with an electrode (notshown) of an associated one of the battery cells 12.

The busbars 16 are typically formed from a high electrical conductivitymaterial such as copper, aluminum or gold. As a non-limiting example, anexterior surface of the busbar 16 is covered with insulating materials(not shown) such as those for electrical cables or plugs to avoidunwanted electrical contact. As shown, the busbars 16 each include amain body 24, a plurality of sockets 26 formed in the main body 24 (orseparately formed and coupled thereto), and a terminal 28 formed in themain body 24 on a surface of the main body 24 opposite the sockets 26.As a non-limiting example, the terminal 28 is one of a conductivedetail, a pin, a post, and an internal clip disposed on a surface of thebusbar 16 opposite to the sockets 26.

Each of the sockets 26 includes an aperture 30 formed therein to receiveone of the tabs 14. Each of the busbars 16 can include any number ofsockets 26. It is understood that the aperture 30 of each of the sockets26 is sized to receive the tab 14 having a support plate 20 coupledthereto. As a non-limiting example, the tab 14 is inserted into theaperture 30 with a force similar to the force typically required forelectronic board installation in electric or electronic devices. Incertain embodiments, the tab 14 coupled to the support plate 20 ispress-fitted into the aperture 30 and no adhesive or welding process isrequired. It is understood that the forced insertion of the tab 14 intothe aperture 30 secures the connection between the battery cells 12 andthe busbar 16 and, through the “wedging effect”, results in a contactforce between the tab 14 and the busbar 16 that maximizes an actual,microscopic contact area, which in turn improves electrical conductanceof the contact surfaces. It is further understood, the forced insertioncauses surface rubbing of the contact interface, which can rupture theoxidation films grown on most metal surfaces exposed to air and hence,reduce the electrical resistance from the tab 14 to the busbar 16.

The control plate 18 includes a plurality of receptacles 32, each of thereceptacles 32 is adapted to receive the terminal of one of the busbars16 for monitoring and controlling a voltage and a current of the batterymodule 10. As shown, each of the receptacles 32 is in electricalcommunication with a connector 33 for transmitting and receivingfeedback and control signals respectively.

Although the busbar-tab insertion process can be performed manually, theroot portion 23 of each of the tabs 14 is typically too soft andflexible to support a force of the insertion resulting from anautomated, high speed assembly operation.

As shown in FIGS. 4-5, the invention conceives a grill fixture 34 tofacilitate automated busbar-tab insertion. The grill fixture 34 includesa plurality of grill rods 36 which are equally spaced and rigidlymounted on the grill carrier 38. The grill carrier 38 is slideablycoupled to a fixture base 40. It is understood that any means ofslideably coupling the grill carrier 38 to the base 40 can be used suchas a track system, for example. In certain embodiments, a tab supportplate 41 is disposed on the fixture base 40 in a pre-determined positionand orientation. As a non-limiting example, the tab support plate 41 iscoupled to the base 40 in a static position.

Each grill rod 36 has a main body 42 with wedge-shaped lead 44 and akeyway slot 46 formed in a fixed face of the grill rod 36. However, themain body 42 can have any shape as desired. In certain embodiments, thekeyway slot 46 is sized to receive the key 22 on the support plate 20 ofthe cell tab 14. It is understood that the keyway slot 46 may beslightly larger than the key 22 to provide clearance for the key 22 tofreely slide within the keyway slot 46.

FIGS. 6-7 illustrate an assembly operation for the battery module 10according to an embodiment of the present invention. Initially, thebattery cells 12 are disposed on the base 40 of the grill fixture 34 ina stacked relationship. As shown, at least one of the tabs 14 isdirectly supported by the tab support plate 41.

The grill carrier 38 is caused to slide relative to the fixture base 40such that each of the grill rods 36 is disposed through a space betweenthe tabs 14 of each adjacent pair of battery cells 12. During sliding,the lead 44 of each of the grill rods 36 flexs the tabs 14 and guidesthe tabs 14 into a fixed spacing, which is determined by a sizing of thegrill rods 36. It is understood that each of the keys 22 on the supportplate 20 of each of the tabs 14 is received in a corresponding keywayslot 46 on the grill rods 36 to facilitate alignment of the tabs 14.

With the tabs 14 firmly supported by the grill rods 36 through thekey-keyway engagement, the busbars 16 are pressed onto the tabs 14.Specifically, each tab 14 is received in the respective aperture 30 ofthe sockets 26 of the busbars 16. Once the busbarsl 6 are secured, thegrill rods 36 are caused to slide out of the stack of the battery cells12 to complete the assembly operation without requiring welding.However, it is understood that in certain embodiments, the tabs 14 canalso be welded to the busbars 16.

As a non-limiting example, nine of the battery cells 12 are shown in thestack. Three adjacent battery cells 12 are arranged in a first parallelunit 48 having a positive (+) one of the tabs 14 aligned with a positive(+) one of the tabs 14 on an adjacent battery cell 12 and a negative (−)one of the tabs 14 aligned with a negative (−) one of the tabs 14 of anadjacent battery cell 12. A second parallel unit 50 is disposed adjacentthe first parallel unit 48, wherein each of the battery cells 12 of thesecond parallel unit 50 are arranged to align the tabs 14 in ajuxtaposed relation compared to the battery cells 12 of the firstparallel unit 48. A third parallel unit 52 is disposed adjacent thesecond parallel unit 50, wherein each of the battery cells 12 of thethird parallel unit 52 is arranged to align the tabs 14 in a juxtaposedrelation compared to the battery cells 12 of the second parallel unit 50(i.e. in the same arrangement as the first parallel unit 48). As afurther example, one of the busbars 16 includes six sockets 26, whereineach of the sockets 26 receives one of the tabs 14, as shown in FIGS.7A-7B. Specifically, three of the adjacent positive tabs 14 of the firstparallel unit 48 are and three negative tabs 14 of the second parallelunit 50 are received in the sockets 26 of the busbar 16 to couple thetabs 14 in series from the first parallel unit 48 to the second parallelunit 50. It is understood that the busbars 16 can be configured to fit aconnection requirement of any number of battery cells 12 in anyconfiguration. As a non-limiting example, another set of the grillcarriers 38 and the grill rods 36 can be applied to an opposite side ofthe battery cells 12 and a plurality of the busbars 16 are disposed onthe battery tabs 14 to complete a busbar connection for each of thebattery cells 12, as shown in FIG. 8.

It is also understood that the individual busbar 16 can be replaced by amonolithic busbar plate (not shown) for connecting the tabs 14 in oneinsertion, eliminating the need of the control plate 18.

Since the busbars 16 are selectively removable from the tabs 14, thebattery module 10 is easily repairable and remanufacturable at a minimaleffort and cost. The battery module 10 maintains a flexibility inserial/parallel connection of the battery cells 12 and minimizes anoccurrence of uneven tab alignment.

From the foregoing description, one ordinarily skilled in the art caneasily ascertain the essential characteristics of this invention and,without departing from the spirit and scope thereof, make variouschanges and modifications to the invention to adapt it to various usagesand conditions.

What is claimed is:
 1. An apparatus for assembling a battery modulehaving a plurality of battery cells, the apparatus comprising: a base; agrill carrier moveable relative to the base; and a grill rod coupled tothe grill carrier, the grill rod having a main body with a longitudinalaxis generally parallel to the base.
 2. The apparatus according to claim1, further comprising a support plate disposed on the base to support atab of one of the battery cells during assembly of the battery module.3. The apparatus according to claim 1, wherein the grill rod includes awedge-shaped lead.
 4. The apparatus according to claim 1, wherein thegrill rod includes a keyway slot formed therein.
 5. The apparatusaccording to claim 4, wherein the keyway slot is formed along thelongitudinal axis of the grill rod.
 6. A method for assembling a batterymodule, the method comprising the steps of: providing an apparatushaving a base, a grill carrier moveable relative to the base, and agrill rod coupled to the grill carrier, the grill rod having a main bodywith a longitudinal axis generally parallel to the base; disposing aplurality of battery cells on the base in a stacked relationship, eachof the battery cells having a pair of tabs extending therefrom; movingthe grill carrier toward the battery cells to dispose the grill rodbetween at least one tab of each of an adjacent pair of the batterycells; and coupling a busbar to the at least one tab of each of anadjacent pair of the battery cells.
 7. The method according to claim 6,wherein at least one of the tabs includes a support plate coupledthereto.
 8. The method according to claim 7, wherein the support plateincludes a key protruding from a surface thereof.
 9. The methodaccording to claim 8, wherein the grill rod includes a keyway slotformed therein to engage the key formed on the support plate.
 10. Themethod according to claim 6, wherein the busbar includes a socket havingan aperture to receive one of the tabs.
 11. The method according toclaim 10, wherein the at least one tab of each of a pair of adjacentbattery cells is press-fitted into a corresponding one of the aperturesof the busbar.
 12. The method according to claim 6, further comprisingthe step of providing a support plate disposed on the base to support atab of one of the battery cells during assembly of the battery module.